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Traveling faster than 65,000 miles per hour and as far as 83 million miles from Earth, the comet Tempel 1 is the ultimate moving target. But on July 4, NASA's Deep Impact probe will take its best shot. Why? Because Tempel 1 likely contains bits of the primordial solar system within its icy shell. Deep Impact's wine barrel-sized impactor will separate from the larger flyby craft and drop onto the comet at 22,800 mph, blasting it with the force of 4.5 tons of TNT. Earthlings from Hawaii to New Zealand should be able to see the blast, which will carve a crater up to seven stories deep. Mean-­while, the flyby will snap pictures of the ancient star stuff that's been kicked up during the collision. But the craft will have to shoot fast - less than 15 minutes after the impactor hits, the flyby's antenna will be hidden in the comet's tail. That should be enough time for planetary scientists to gather some 365 megabytes of information about how the sun and planets were created.